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How do I pull a value from an array embedded within an array of objects in MongoDB? [duplicate]

I have a document structure something along the lines of the following:
{
"_id" : "777",
"someKey" : "someValue",
"someArray" : [
{
"name" : "name1",
"someNestedArray" : [
{
"name" : "value"
},
{
"name" : "delete me"
}
]
}
]
}
I want to delete the nested array element with the value "delete me".
I know I can find documents which match this description using nested $elemMatch expressions. What is the query syntax for removing the element in question?

To delete the item in question you're actually going to use an update. More specifically you're going to do an update with the $pull command which will remove the item from the array.
db.temp.update(
{ _id : "777" },
{$pull : {"someArray.0.someNestedArray" : {"name":"delete me"}}}
)
There's a little bit of "magic" happening here. Using .0 indicates that we know that we are modifying the 0th item of someArray. Using {"name":"delete me"} indicates that we know the exact data that we plan to remove.
This process works just fine if you load the data into a client and then perform the update. This process works less well if you want to do "generic" queries that perform these operations.
I think it's easiest to simply recognize that updating arrays of sub-documents generally requires that you have the original in memory at some point.
In response to the first comment below, you can probably help your situation by changing the data structure a little
"someObjects" : {
"name1": {
"someNestedArray" : [
{
"name" : "value"
},
{
"name" : "delete me"
}
]
}
}
Now you can do {$pull : { "someObjects.name1.someNestedArray" : ...
Here's the problem with your structure. MongoDB does not have very good support for manipulating "sub-arrays". Your structure has an array of objects and those objects contain arrays of more objects.
If you have the following structure, you are going to have a difficult time using things like $pull:
array [
{ subarray : array [] },
{ subarray : array [] },
]
If your structure looks like that and you want to update subarray you have two options:
Change your structure so that you can leverage $pull.
Don't use $pull. Load the entire object into a client and use findAndModify.

MongoDB 3.6 added $[] operator that facilitates updates to arrays that contain embedded documents. So the problem can be solved by:
db.test.update(
{ _id : "777" },
{$pull : {"someArray.$[].someNestedArray" : {"name":"delete me"}}}
)

As #Melkor has commented (should probably be an answer as itself),
If you do not know the index use:
{
_id: TheMainID,
"theArray._id": TheArrayID
},
{
$pull: {
"theArray.$.theNestedArray": {
_id: theNestedArrayID
}
}
}

From MongoDB 3.6 on you can use arrayFilters to do this:
db.test.update(
{ _id: "777" },
{ $pull: { "someArray.$[elem].someNestedArray": { name: "delete me" } } },
{ arrayFilters: [{ "elem.name": "name1"}] }
)
see also https://docs.mongodb.com/manual/reference/operator/update/positional-filtered/index.html#update-all-documents-that-match-arrayfilters-in-an-array

Other example and usage could be like this:
{
"company": {
"location": {
"postalCode": "12345",
"Address": "Address1",
"city": "Frankfurt",
"state": "Hessen",
"country": "Germany"
},
"establishmentDate": "2019-04-29T14:12:37.206Z",
"companyId": "1",
"ceo": "XYZ"
},
"items": [{
"name": "itemA",
"unit": "kg",
"price": "10"
},
{
"name": "itemB",
"unit": "ltr",
"price": "20"
}
]
}
DELETE : Mongodb Query to delete ItemB:
db.getCollection('test').update(
{"company.companyId":"1","company.location.city":"Frankfurt"},
{$pull : {"items" : {"name":"itemB"}}}
)
FIND: Find query for itemB:
db.getCollection('test').find(
{"company.companyId":"1","company.location.city":"Frankfurt","items.name":"itemB"},
{ "items.$": 1 }
)
3.UPDATE : update query for itemB:
db.getCollection('test').update
(
{"company.companyId":"1","company.location.city":"Frankfurt","items.name":"itemB"},
{ $set: { "items.$[].price" : 90 }},
{ multi: true });

Matching certain value in JSON Array using match() or find() in JavaScript

I'm looking for a function or method to overcome this issue
Here is the JSON Array
[{
"type": "radar",
"detail": [{
"subject": "sub1"
}, {
"subject": "sub2"
}]
}, {
"type": "bar",
"detail": [{
"subject": "sub1"
}, {
"subject": "sub2"
}]
}]
I'm hoping to identify the value of "type" which in this case would be "radar" and "bar"，and match with the variable x。
Here's the code:
for(x in myarray)
{
if(myarray[x]['type']=="bar")
{
console.log("equal");
}
else
{
console.log("no result");
}
}
With this code,the result on the website console would be both "equal" and "no result",while I wish to print "equal" only.I understand the logic error in this code,but I couldn't figure out the correct way to fix it.

You can use Array.some for this which return true or false if one of the array element match with type "bar" then It will return true otherwise false
var data = [{
"type": "radar",
"detail": [{
"subject": "sub1"
}, {
"subject": "sub2"
}]
}, {
"type": "bar",
"detail": [{
"subject": "sub1"
}, {
"subject": "sub2"
}]
}]
if (data.some(val => val.type == "bar"))
console.log("Equal")
else
console.log("No record found");

let myArr = [
{ "type":"radar",
"detail": [
{ "subject":"sub1" },
{ "subject":"sub2" }
]
},
{ "type":"bar",
"detail": [
{ "subject":"sub1" },
{ "subject":"sub2" }
]
}
]
for(let x of myArr){
if(x.type === 'bar'){ console.log('equal')}
else { console.log('no result')}
}
In order to understand what went wrong with your code, first when you have a for loop, you need to have a let/var keyword as below:
for(let x of myArr)
Secondly, instead of using for..in loop, which it meant for looping property of objects, use for..of loop which meant for looping array.
Third, while looping myArr, each and every element x is an object and type is the property, so just use x.type to make the comparison.
Lastly, as others have mentioned, Array#some / Array#find is a better way to deal with finding existence of element in an array

Since the for loop runs for each object in the array, the first console log for equal is for matched type and second console log is for the unmatched type. So, to get only one console and to write more appropriate code, you can use Array.find() and then add a if-else block for that. Something like this:
var myarray = [ { "type":"radar", "detail": [{ "subject":"sub1" }, { "subject":"sub2" }] }, { "type":"bar", "detail": [{ "subject":"sub1" }, { "subject":"sub2" }] } ];
var match = myarray.find(({type}) => type === "bar");
if(match) {
console.log("equal");
} else {
console.log("no result");
}

Angular bind to filtered count

I have this array:
[
{
type: "hhh",
items: [
{
"name": "EGFR",
"type": "a",
"selected": true
}
]
},
{
type: "aaa",
items: [
{
"name": "mm",
"type": "b",
"selected": false
}
]
},
{
type: "ii",
items: [
{
"name": "pp",
"type": "bb",
"selected": true
}
]
}
]
I want to show a counter of the items with selected property "true".
I want it to be changed real time when change.
(Without watch and function)
Thnaks!

Here is the way:
var current_selected = {
get amount(){
var res = 0;
arr.forEach(function(item, i, arr) {
if (item.items[0].selected) res++;
})
return res;
}
}
Calling:
current_selected.amount
Fiddle

You can use JsonPath to get the count. Also using JsonPath has an added advantage of working on complex json structure. For the example you gave, you just need to include jsonpath js file and use the following in your script:
console.log(arr);
var filtered = jsonPath(arr, "$.[*].items[?(#.selected==true)]");
console.log(filtered);
console.log(filtered.length);
where arr is your json structure.
JsonPath can be got from :
https://code.google.com/archive/p/jsonpath/downloads
JsonPath help:
http://goessner.net/articles/JsonPath/
There might be updated version in other sources but that was the one I had worked on

Convert objects to array in javascript

I really want to convert a object to array but my codes doesn’t worked.
data = "errors": {
"user": {
"name": "empty"
},
{
"length": "exceeds"
},
"title": {
"name": "empty"
},
{
"length": "exceeds"
}
}
Now I want to make them:
data = ["empty", "exceeds", "empty", "exceeds"];
What I’ve done so far is:
var arr = Object.keys(data[i].data.errors).map(function(k) {
return data[i].data.errors[k]
});
console.log(arr);
But the output is not what I expected. Please help. Thank very much.

If you always know the keys of the inner objects are going to be name and length a short way might be:
var out = Object.keys(data.errors).reduce(function (p, c) {
return p.concat([data.errors[c].name, data.errors[c].length]);
}, []);
DEMO

How to parse a JSON array string in JavaScript?

I have an JSON array like this
var filter_value_data = [{"Status":[{"name":"Open","id":"1"},{"name":"Pending","id":"2"},{"name":"Resolved","id":"3"},{"name":"Closed","id":"4"},{"name":"Evaluation","id":"5"}]},{"Payment Status":[{"name":"Paid","id":"10"},{"name":"UnPaid","id":"11"},{"name":"Part Paid","id":"12"}]},{"Priority":[{"name":"Low","id":"6"},{"name":"Medium","id":"7"},{"name":"High","id":"8"},{"name":"Urgent","id":"9"}]}]
I have tried filter_value_data["Status"] which is obviously wrong. How do I get the JSON elements for Status using the names like Status,Payment Status?

filter_value_data is an array (having []), so use filter_value_data[0].Status to get the first element-object with property "Status".
It is always good to format your code in order to see the hierarchy of the structures:
var filter_value_data = [
{
"Status": [
{
"name": "Open",
"id": "1"
}, {
"name": "Pending",
"id": "2"
}, ...
]
}, {
"Payment Status": [
{
"name": "Paid",
"id": "10"
}, ...
]
}, {
"Priority": [
{
"name": "Low",
"id": "6"
}, ...
]
}
];

With your current JSON you can't get the elements with the name alone.
You can get Status with filter_value_data[0]['Status'] and Payment status with filter_value_data[1]['Payment Status'].
This is because the keys are in seperate objects in the array.
In order to get them with filter_value_data['Status'] you need to change your JSON to
var filter_value_data = {
"Status":[
{"name":"Open","id":"1"},
{"name":"Pending","id":"2"},
{"name":"Resolved","id":"3"},
{"name":"Closed","id":"4"},
{"name":"Evaluation","id":"5"}
],
"Payment Status":[
{"name":"Paid","id":"10"},
{"name":"UnPaid","id":"11"},
{"name":"Part Paid","id":"12"}
],
"Priority":[
{"name":"Low","id":"6"},
{"name":"Medium","id":"7"},
{"name":"High","id":"8"},
{"name":"Urgent","id":"9"}
]
};
I wrote this on my phone so it's not as well-formatted as usual. I'll change it ASAP.

With your current JSON, created a result which might be helpful for you.
JS:
$.each(filter_value_data,function(ind,val){
var sta = val.Status; // Status Object get displayed
for(var i=0;i<sta.length;i++){
var idVal= sta[i].id;
var nameVal = sta[i].name;
Statusarray.push(idVal,nameVal);
console.log(Statusarray);
}
})
FiddleDemo

You can use below code, it will return status object
filter_value_data[0]['Status']
filter_value_data[0]['Payment Status']
to get Single value you use :
filter_value_data[0]['Status'][0]['name']